The invention relates to a connecting rear wall having plug-and-socket devices arranged on a connecting board for making mutual contact between electronic and/or electromechanical plug-in modules in subracks, and having the potential leads of at least one power supply unit.
Modules assembled using plug-in design and operated with one another in a subrack are in general use, in particular for equipment in data systems technology. High demands are placed on this equipment with regard to the suppression of high-frequency interfering radiation. Since the production of such interference on the modules cannot be avoided, the latter and/or the subrack are generally designed as a screening cage.
A problem arising in this case is the connecting rear wall, which on the one hand leaves the rear of the subrack open, and on the other hand carries connecting lines which act as transmitting antennas for the interfering radiation. It is difficult to screen them, in particular in the case of subracks into which modules can be plugged from two opposites sides and in the case of which, therefore, the connecting rear wall is situated in the middle of the subrack. Such a subrack is disclosed, for example, in DE 36 08 046 A1. It is already known from U.S. Pat. No. 3,992,686 to construct the connecting rear wall as a multi-layer printed circuit board, and in this case to use one layer to carry the zero potential and thus as a large-area high-frequency screen (ground plane). A further layer carries a supply voltage.
It is disadvantageous in this arrangement that the screen has as small cross-sectional area, and is thus generally--although mostly at zero potential--suitable only conditionally as a current-carrying conductor for the power supply. The same holds for the layer carrying the supply voltage. Consequently, use is made in addition of conductors of relatively large cross-section to carry the current. However, from the point of view of electronic engineering, the latter form with the screen potential loops which can often be mastered only with difficulty.
It is an object of the invention to provide a connecting rear wall of the type mentioned at the beginning which has an improved screening effect against high-frequency interfering radiation, and is simple to disassemble for the purpose of enabling ease of recycling.